The present invention is related to the catalytic protein subunit of human telomerase. The invention provides methods and compositions relating to medicine, immunology, and molecular biology.
The following discussion is intended to introduce the field of the present invention to the reader. The citation of references in this section should not be construed as an admission of prior invention.
The telomerase ribonucleoprotein complex is a specialized polymerase that maintains telomeres, the specialized structures at the ends of eukaryotic chromosomes. The length and integrity of telomeres in a cell is correlated with the entry of the cell into a senescent stage (i.e., loss of proliferative capacity), or, alternatively, the ability of a cell to escape senescence. Of particular interest is the correlation observed between telomerase activity in human and other mammalian cells and the development of a neoplastic phenotype. For example, telomerase activity is detected in immortal cell lines and a diverse set of tumor tissues, but is not detected (i.e., was absent or below the assay threshold) in normal somatic cell cultures or normal tissues adjacent to a tumor (see, U.S. Pat. Nos. 5,629,154; 5,489,508; 5,648,215; and 5,639,613; also see, Morin, 1989, Cell 59: 521; Shay and Bacchetti, 1997, Eur. J. Cancer 33:787; Kim et al., 1994, Science 266:201 1; Counter et al., 1992, EMBO J. 11:1921; Counter et al., 1994, Proc. Natl. Acad Sci. U.S.A. 91, 2900; Counter et al., 1994, J. Virol. 68:3410). Moreover, a correlation between the level of telomerase activity in a tumor and the likely clinical outcome of the patient has been reported (e.g., U.S. Pat. No. 5,639,613; Langford et al., 1997, Hum. Pathol. 28:416).
Thus, telomerase plays an important role in the control of cell proliferation and in tumorigenesis. For these and other reasons, human telomerase is an ideal target for preventing and treating human diseases relating to cellular proliferation and senescence, such as cancer. The present invention provides immunological methods for preventing and treating these and other diseases in humans and nonhuman animals.
In one aspect, the present invention provides a method of activating a T lymphocyte by contacting the T lymphocyte with a dendritic cell that expresses a telomerase reverse transcriptase (TRT) polypeptide encoded by a recombinant nucleic acid. In various embodiments of the invention, the TRT polypeptide is a human TRT (hTRT) polypeptide, and may have the sequence set forth in FIG. 1, or may have a subsequence thereof. In one embodiment, the hTRT polypeptide is full-length. In one embodiment, the dendritic cell is a human cell. The dendritic cell may contact the T lymphocyte in vivo or in vitro.
In a related aspect, the invention provides a recombinant dendritic cell which comprises a recombinant TRT expression cassette. In one embodiment, the recombinant expression cassette is transduced into a stem cell, and the stem cell is then differentiated into the dendritic cell. In one embodiment, the stem cell is differentiated in vitro. The invention also provides a pharmaceutical composition comprising the aforementioned dendritic cell and a pharmaceutically acceptable carrier.
In another aspect, the invention provides a method of eliciting an immune response in a human patient by (a) obtaining human dendritic cells, (b) transducing a TRT expression cassette into the cells so that they are capable of expressing a hTRT polypeptide, and (c) administering the cells to the human patient. In certain embodiments, the dendritic cells are isolated from the human patient to which they are administered, and/or are obtained from hematopoietic precursor cells.
In yet another aspect, the invention provides a method of eliciting an immune response in a human patient by (a) obtaining human dendritic cells, (b) pulsing the cells with a hTRT antigen, and (c) administering the cells pulsed with the hTRT antigen to the human patient. In certain embodiments, the dendritic cells are isolated from the human patient to which they are administered, and/or are obtained from hematopoietic precursor cells. In one embodiment the cells are pulsed with one or more hTRT antigenic peptides that are less than 50 amino acid residues in length 122
In another aspect, the invention provides a method for identifying a cell expressing hTRT. According to the method, a dendritic cell is transduced with a recombinant expression cassette comprising a nucleic acid encoding a hTRT polypeptide; a T lymphocyte is contacted with the transduced dendritic cell, thereby providing an activated T lymphocyte; and a target cell is contacted with the activated T lymphocyte. The effect of the activated T lymphocyte on the target cell is then monitored.